The prior art includes numerous different designs for open-ended wrenches capable of working with a ratcheting action. All of the prior art wrenches known to the inventors have one or more significant defects which limit their usefulness and have prevented their widespread adoption. A particular disadvantage of many prior ratcheting open-ended wrenches is that they are bulky. This makes them incapable of being used in tight quarters. SAE has defined an envelope within which open-ended wrenches should fit. The SAE envelope is described in the SAE Aeronautical Drafting Manual, and in Machinery's Handbook 23rd Edition, Industrial Press Inc., N.Y., N.Y., 1988 at page 1299.
In most cases it is impossible to make bulky prior art ratcheting open-ended wrenches compact enough to comply with the SAE specifications without rendering them too weak to use reliably. There is a need for simple effective ratcheting open-ended wrenches which are sufficiently compact to comply with the SAE specifications for open-ended wrenches.
The prior art open-ended ratcheting wrenches also suffer from other disadvantages. Some designs are very complicated. Wrenches according to these designs are undesirable because they have many parts which can fail and are also expensive to make. Other prior wrenches are not sufficiently robust to turn a fastener with sufficient torque. Other prior art wrenches are awkward to engage with the head of a fastener. Other prior art wrenches will not properly grip fasteners which have rounded corners. Some prior art wrenches will slip on a fastener unless the fastener is completely bottomed in the wrench opening.
Prior inventors have struggled to provide open ended ratcheting wrenches having fine ratchet increments such as 45 degrees, 30 degrees, or even 15 degrees. A fine ratchet increment can allow fastener drive heads to be turned in tight quarters. However, in the quest for fine ratchet increments the designers of such previous wrenches have sacrificed simplicity, durability and usability. Most prior art wrenches which have a fine ratchet increment cannot be used reliably to turn fastener heads which have rounded corners. Furthermore, most such wrenches cannot be used effectively unless they are held perpendicular to the axis of rotation of the drive head being turned.
Some prior art ratcheting wrenches have no moving parts at all. These wrenches suffer from the disadvantage that they do not work well on fasteners with rounded corners. These wrenches must have one very short jaw. Consequently they can be used effectively only when a fastener is fully bottomed in the wrench opening.
Gajo, U.S. Pat. No. 5,582,082 shows a ratcheting open ended wrench having a moving jaw which both slides and pivots. This wrench is not as durable as would be desirable. The sliding action of the movable jaw can result in excessive wear. Furthermore, the movable jaw can become permanently deformed if the wrench is used aggressively. The Gajo design requires slots in the jaw which create areas of weakness.
There are a large number of prior wrenches capable of operating with a ratcheting action which include an opening defined by a movable jaw pivotally attached to a fixed jaw. In many of these wrenches, and in contrast to the wrench of this invention, the movable jaw rotates about a pivot point located on the same side of the opening as the gripping surfaces of the movable jaw. Some examples of such wrenches are Hewitt et al, U.S. Pat. No. 2,277,400; Hesse, U.S. Pat. No. 1,050,215; Halstead et al, U.S. Pat. No. 770,574; U.S. Pat. No. 4,324,159; Wylie, U.S. Pat. No. 5,018,412; Page, Canadian patent No. 271,730; De Santis, U.S. Pat. No. 4,554,847; and Meyer, U.S. Pat. No. 1,015,504.
There are a large number of prior ratchet type wrenches having two independently movable jaws. These wrenches are generally undesirably complicated and are therefore expensive to make. Furthermore, they have numerous parts which can wear out. some examples of such wrenches are disclosed in Bartlett, Canadian patent No. 519,086; Dyck, Canadian patent Nos. 850,359 and 1,004,514; Dyck et al., U.S. Pat. No. 3,921,474; Ginsburg, U.S. Pat. No. 1,183,371; Wilson, U.S. Pat. No. 3,878,741; Meggs et al., U.S. Pat. No. 4,065,986; Logan, U.S. Pat. No. 4,584,913; and Nitschmann, U.S. Pat. No. 4,718,315.
Despite the wide variety of ratcheting open ended wrenches described in the prior art there remains a need for a compact open ended wrench which is capable of providing a ratcheting action and yet improves on the capabilities of prior art wrenches.